Devices and methods for hip replacement

ABSTRACT

Devices and methods for use in hip replacement surgery can incorporate computer models of a patient&#39;s acetabulum and surrounding bone structure, a first patient-specific jig designed from the computer model and configured to correspond to a final installation position and orientation of a prosthetic him implant, a second patient-specific jig, also designed from the computer model, configured to refine the procedure, if necessary, following use of the first patient-specific jig, and/or a third patient specific jig, designed from the computer model, configured to refine the procedure, if necessary, following use of the first and second patient-specific jigs, allowing the surgeon to properly position and orient the hip prosthesis. Also shown and described are novel devices for implanting an acetabular cup.

BACKGROUND

1. Technical Field

The present disclosure relates to devices and methods for the replacement of joints, and more particularly, to patient-specific hip replacement devices, including methods of manufacturing and using such devices for achieving accurate hip replacement based on computer generated imaging of a patient.

2. Background of the Invention

One known method of treating hip and other joints with arthritis and other medical conditions is to replace surfaces of articulating joints with prosthetic devices through surgical procedures. It is critical that such prosthetic devices are accurately designed and manufactured, and are installed correctly in order to relieve pain and provide an effective treatment method for such ailments. An orthopedic surgeon performing such joint replacement on a patient seeks to ensure, through surgery, adequate placement of the prosthetic and proper reconstruction of the joint being replaced. Prosthetic components used to replace a joint may placed optimally by templates and jigs according to the unique anatomy of a patient before surgery occurs. A particular patient's bone structure symmetry is one important consideration that a surgeon must consider when performing joint replacement surgery. Additionally, malposition of joint replacement prosthetics can result in premature wear of the bearing surfaces, which may require additional surgeries to correct.

In the case of a hip, the condition of the patient's joint may require a partial or total replacement. A partial hip replacement involves replacing the femoral head (the ball) of the damaged hip joint; however, the acetabulum (the socket) is not replaced in a partial hip replacement surgery. A total hip replacement includes replacing both the femoral head and the acetabulum with prosthetic devices. The femoral head is replaced with a femoral prosthetic that typically includes a head portion and a stem. The stem extends into the femur of the patient and is utilized to secure the femoral device to the femur, with the head portion protruding out from the femur. The acetabulum is then resurfaced and replaced with a cup-shaped acetabular device. The cup-shaped acetabular device provides a bearing surface for the head portion of the femoral prosthetic to allow a desirable amount of range of motion via the joint upon total hip replacement.

To replace the acetabulum effectively, a surgeon will typically enlarge the acetabulum with a reamer machine and reamer head to create a resurfaced cavity to receive a prosthetic acetabular cup, which may or may not be secured by cement or bone screws. One particular issue of concern during the reaming portion of the surgery is that the cutting portion of the reamer is hemispherical while the prosthetic acetabular cup is typically sub-hemispherical. If the acetabulum is reamed too deeply, the prosthetic acetabular cup will be positioned too deep within the reamed cavity. If the acetabulum is reamed too shallowly, the prosthetic acetabular cup will not be positioned deep enough. If the acetabulum is reamed at an improper angle, the prosthetic acetabular cup will not be installed properly. These imperfections can cause malalignment of the prosthetic hip joint. Thus, accurate reaming of the acetabulum and accurate positioning of the prosthetic acetabular cup are critical.

With the assistance of computer generated data derived from CT, MRI, or other scans, surgeons can more effectively determine proper alignment and positioning of the prosthetic acetabular cup in a patient through 3D modeling and rendering. While some surgeons use lasers during surgery in an attempt to properly place the prosthetic acetabular cup; however, accuracy and simplicity of existing devices and methods remain limited due to a variety of factors.

BRIEF SUMMARY

The present disclosure pertains to patient-specific hip replacement devices and methods of designing and manufacturing such devices for achieving accurate acetabular component placement during hip replacement surgery based on computer generated imaging of a particular patient. When an orthopedic surgeon recommends total hip replacement surgery for a particular patient, a variety of images may be obtained utilizing CT, MRI, and other scans to generate 3D modeling of the patient's bone structure, particularly the femur, the pelvic bone, and the coxal (hip) bone. From such 3D models, the surgeon may determine the specific, final location and orientation of an acetabular cup to be secured to the patient's acetabulum during surgery. Once the final location and orientation of the acetabular cup is determined, the surgeon (utilizing 3D images) may create a first patient-specific jig and a second—and in some cases a third—patient-specific jig to be inserted into the patient's acetabulum during the surgery to ultimately achieve accurate positioning of the prosthetics to be installed in the patient.

The first patient-specific jig may be designed and manufactured based on a first patient-specific acetabulum male portion, while the second patient-specific jig may be designed and manufactured based on a second patient-specific acetabulum male portion. The first and second patient-specific acetabulum male portions can be developed as either physical components via a prototyping machine or visual representations in a 3D modeling software program based upon the 3D images of the patient. The male portion may or may not fully contact the patient's native acetabulum.

The first patient-specific jig can be a hemispherical shaped device or a sub-hemispherical shaped device, and can be comprised of composite material or other materials. The first patient-specific jig may include at least three alignment members for attachment to specific portions of the jig based on the specific bone structure of the patient's coxal bone. The at least three alignment members may assist with proper alignment of the first patient-specific jig in the patient's acetabulum during surgery. The three alignment members may include first, second, and third alignment members that are positioned at specific outer portions of the first patient-specific jig.

In some embodiments, the first, second, and third alignment members are designed and adapted to be hooked on or engaged with (or otherwise positioned at) particular portions of the coxal bone adjacent to the acetabulum to stabilize and properly orient the first patient-specific jig into the acetabulum during surgery. The first alignment member may be positioned on the first patient-specific jig to engage a particular portion of the medial rim of the acetabulum of the coxal bone. The second alignment member may be positioned on the first patient-specific jig to engage a particular portion of the greater sciatic notch of the coxal bone. The third alignment member may be positioned on the first patient-specific jig to engage a particular portion of the obturator foramen of the coxal bone. These alignment members may contact any three areas of bone peripheral to the acetabulum. Thus, the first patient-specific jig includes three reference points/members, specific to the patient's acetabulum of the coxal bone, to properly align the first patient-specific jig in the acetabulum during surgery and provide for proper orientation of the reaming machine when resurfacing the acetabulum.

The three alignment members may each comprise a pair of hooks or other devices that provide sufficient engagement with the particular portions of the coxal bone, as determined by the surgeon during preoperation. A person having ordinary skill in the art when reviewing this disclosure will understand that the three alignment members may be secured or removably attached or abutted to the first patient-specific jig by any currently or later known suitable means or attachment methods. The three alignment members may pivot, swivel or otherwise move relative to the first patient-specific jig, or they may be relatively immovable or inflexible to provide sufficient force against respective portions of the coxal bone to ensure proper orientation of the first patient-specific jig.

An aperture may be provided radially into or through the first patient-specific jig. The aperture is adapted to receive a guide pin or post extension through the aperture during surgery. The guide pin or extension is placed into the aperture and is removably secured to the coxal bone of the patient in a particular orientation and at a particular depth, as determined by the surgeon during preoperation. The first patient-specific jig is then removed while the guide post remains positioned in the coxal bone at the desired angle and position. The guide post may then serve as a guide for the reaming machine to accurately ream (resurface) the acetabulum to a predetermined depth and orientation for receiving the acetabular cup. The guide post and the reamer may have the same or similar central axes, as with conventional reaming machines and processes. In some embodiments the guide post may be removed prior to reaming and a surgeon at his discretion may use the guide post sinus tract as a guide to reaming without the guide post at a desired angle and to a desired depth.

As discussed above, it is critical to ream the acetabulum accurately and as determined during preoperation. Accordingly, the second patient-specific jig may be provided to assist in determining accurate reaming and proper alignment of the acetabular cup before the cup is implanted into the patient's acetabulum. As indicated below, a third patient-specific jig may also be used to progressively prepare the acetabulum to properly receive the prosthetic acetabular cup.

The second patient-specific jig may be designed and manufactured based on the second patient-specific male portion, but it may also be based on the first patient-specific male portion. The second patient-specific jig may include at least three alignment members, which may be based on the same or similar positions as the first, second, and third alignment members of the first patient-specific jig, or the positions may be different depending upon the patient's anatomy. The second patient-specific jig may also include an aperture having the same or similar position and orientation as the aperture in the first patient-specific jig, or it may be different. The second patient-specific jig may also have an axial length that is greater than a corresponding axial length of the first patient-specific jig due to the fact that the second patient-specific jig is utilized after some or all of the reaming of the acetabulum has occurred.

After the surgeon has removed the first patient-specific jig and reamed the acetabulum to a predetermined depth and orientation, the reamer device is removed from the acetabulum and the guide post may remain attached to the coxal bone or, in some instances, may be removed. The surgeon may then position the second patient-specific jig into the reamed acetabulum without a pin or, alternatively, onto the original guide pin or post extension, or alternatively over a different pin or post extension used to align the second patient-specific jig. Using the particular shape and size of the second patient-specific jig and, where applicable, the alignment of the aperture through the jig, the surgeon may then rotate and position the second patient-specific jig in the reamed acetabulum to determine whether additional reaming is required in one or more quadrants, or whether the acetabulum has been reamed accurately to receive the prosthetic acetabular cup. In furtherance of such determination, the surgeon may also utilize the alignment members attached to the second patient-specific jig, if they were designed and manufactured for attachment to the jig; it may be that the aperture and the shape of the second patient-specific jig is sufficient for purposes of accurate alignment of the prosthetic acetabular cup.

In some instances, if adequate remaining in any direction has not been accomplished and confirmed with only one or two jigs, there may be a need for additional reaming after which a third jig may be used. The third patient specific jig may be similar or different in regards to alignment members and guide post aperture orientation as the first and/or second patient specific jigs.

Once accurate reaming is accomplished through utilizing some or all of the above described devices and methods, the surgeon may then implant or secure the acetabular prosthetic cup to the reamed acetabulum in a traditional manner, such as with or without screws and with or without cement and with or without use of a guide pin or post extension.

The predetermined orientation of the apertures and the alignment members of both the first and second (and, as applicable, third) patient-specific jigs may provide the surgeon with a quick, accurate means to properly resurface the acetabulum without the use of additional devices and machines. This is possible because the positions of the alignment members of the first, second and third patient-specific jigs are based upon the patient's bone structure, thereby providing three reference points to accurately utilize the first jig, the guide post, the reamer, and the second and third jigs, as planned during preoperation based upon the 3D modeling images of the patient.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1-4 are flow diagrams illustrating steps for pre-operative imaging and planning for a joint replacement procedure, according to an aspect of the present invention.

FIG. 4A schematically illustrates a system for carrying out the steps of FIGS. 1-4.

FIGS. 5 and 6 are flow diagrams illustrating steps for performing a joint replacement procedure, according to an aspect of the present invention.

FIG. 7 is a front view of a pelvic bone.

FIG. 8 is a top view of a prosthetic implant seated in the pelvic bone of FIG. 7.

FIG. 9A is a top view of a patient-specific jig mounted on the pelvic bone of FIG. 7 according to one embodiment.

FIG. 9B is a partial cross-sectional view of the pelvic bone of FIG. 7 and a side view of the patient-specific jig of FIG. 9A.

FIG. 10A is an isometric view of a first patient-specific jig according to one embodiment.

FIG. 10B is an elevational view of the first patient-specific jig of FIG. 10A.

FIG. 11A is an isometric view of a second patient-specific jig according to one embodiment.

FIG. 11B is an elevational view of the second patient-specific jig of FIG. 11A.

FIG. 12A is an isometric view of a third patient-specific jig according to one embodiment.

FIG. 12B is an elevational view of the third patient-specific jig of FIG. 8.

FIG. 13A is a side view of a first patient-specific jig positioned in an acetabulum and a guide post positioned through said jig and secured to the acetabulum.

FIG. 13B is a side view of the pelvic bone showing the first patient-specific jig positioned in the acetabulum.

FIG. 14 is a cross-sectional view of a reaming tool positioned in the acetabulum.

FIG. 15A is a side view of a second patient-specific jig positioned in an acetabulum and a supplemental guide post positioned through said jig and secured to the acetabulum.

FIG. 15B is a side view of the pelvic bone showing the second patient-specific jig positioned in the acetabulum 15A.

FIG. 16 is a cross-sectional view of a reaming tool positioned in the acetabulum.

FIG. 17A is a side view of a third patient-specific jig positioned in the acetabulum and the supplemental guide post of FIG. 15A.

FIG. 17B is a top view of the third patient-specific jig positioned in the acetabulum as shown in FIG. 17A.

FIG. 18 is an isometric view of an impactor tool used to install a prosthetic implant in a reamed acetabulum according to one aspect of the present disclosure.

FIG. 19 is an isometric view of a cannulated acetabular impactor according to an embodiment of the present invention.

FIG. 20 is an end view of the cannulated acetabular impactor of FIG. 19.

FIG. 21 is a partial cross-sectional view of a prosthetic implant in a reamed acetabulum that is being installed with the impactor tool of FIG. 18 and the cannulated actabular impactor of FIG. 19, according to one aspect of the present disclosure.

FIG. 22 is a cross-sectional view of a portion of another cannulated acetabular impactor according to an alternate embodiment of the invention.

DETAILED DESCRIPTION

As mentioned above, the methods and systems of the present invention are based at least in part on pre-operating (pre-operative) imaging and at least in part on orthopedic surgical procedures based upon the pre-operative methods and systems. As is understood in the art, pre-operative imaging has a number of different purposes and generally is performed in order to subsequently guide the surgeon during the surgical procedure, allow for patient-specific tools and/or implants to be formed, etc. The present disclosure is part of a system for designing and constructing one or more patient-specific jigs for use in an orthopedic surgical procedure in which an acetabular component is prepared, orientated and implanted. The referenced systems and methods are now described more fully with reference to the accompanying drawings, in which one or more illustrated embodiments and/or arrangements of the systems and methods are shown. Aspects of the present systems and methods can take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.), or an embodiment combining software and hardware. One of skill in the art can appreciate that a software process can be transformed into an equivalent hardware structure, and a hardware structure can itself be transformed into an equivalent software process. Thus, the selection of a hardware implementation versus a software implementation is one of design choice and left to the implementer. Throughout this disclosure, the term “prosthetic implant” and “acetabular component” refer to cup-shaped implants that are installed into patients during hip replacement surgery.

FIGS. 1-4 are flow diagrams illustrating methods pertaining to pre-operative imaging and planning according to aspects of the present invention. FIG. 4A shows a system for carrying out the methods of the present disclosure, such as those described with reference to FIGS. 1-4. As a preliminary matter, FIG. 4A is a simplified system 410 of devices that may be used to carry out the methods of the present disclosure. The system 410 comprises a computing system 412 coupled to an imaging system 414 that captures and transmits patient image data to the computing system 412. The computing system 412 processes such data and transmits the data to the display device 416 for display of images and other data. An input device 418 receives input from a computer or an operator (such as a surgeon) and transmits inputted information to the computing system 412 for processing. Such systems are well known in the art and will not be described in greater detail. The imaging system 412 may include a bone imaging machine for forming three dimensional image data from bone structure of a patient. The computing system 412 may include a patient-specific device generator for processing and generating images, and a patient-specific device converter for generating design control data. A manufacturing machine 420 receives the control data from the computing system 412 for making patient-specific various jigs.

In FIG. 1, a method 100 according to an embodiment starts at 101. At 102, a bone imaging machine generates a bone surface image from three dimensional image data from bone structure of a patient. At 104, a patient-specific device generator generates a prosthesis implant image superimposed in an acetabulum of the bone surface image. The implant in the image is positioned in its final, implanted position and orientation, regardless of the state of the patient's bone. The jigs created from the present invention will be designed to modify the bone such that the implant will be properly positioned at the end of the procedure.

At 106, the patient-specific device generator generates a first-patient specific jig image superimposed proximate the acetabulum of the bone surface image according to the installation position. At 108, a patient-specific device converter generates control data from the first patient-specific jig image and ends or moves to 110. At 110, the patient-specific device generator generates a second patient-specific jig image superimposed in the acetabulum of the bone surface image and ends or moves to 112. At step 112, the patient-specific device generator generates a third patient-specific jig image superimposed in the acetabulum of the bone surface image and ends.

FIG. 2 shows a method 200 according to an aspect of the present disclosure. At 202, a patient-specific device generator generates a guide post image at least partially positioned through an acetabulum of the bone surface image. At 204, the patient-specific device generator generates a first patient-specific jig image superimposed in the acetabulum of the bone surface image according to the installation position. At 206, the patient-specific device generator generates an aperture image through the body image of the second patient-specific jig image and ends.

FIG. 3 shows a method 300 according to an aspect of the present disclosure. At 302, a patient-specific device generator generates a guide post image at least partially positioned through an acetabulum of the bone surface image. At 304, the patient-specific device generator generates a second patient-specific jig image superimposed in the acetabulum of the bone surface image according to the installation position. At 306, the patient-specific device generator generates an aperture image through the body image of the first patient-specific jig image and ends.

FIG. 4 shows a method 400 according to an aspect of the present disclosure. At 402, a patient-specific device generator generates a guide post image at least partially positioned through an acetabulum of the bone surface image. At 404, the patient-specific device generator generates a third patient-specific jig image superimposed in the acetabulum of the bone surface image according to the installation position. At 306, the patient-specific device generator generates an aperture image through the body image of the third patient-specific jig image and ends.

As discussed above, FIG. 4A shows a system 410 for carrying out the methods of FIGS. 1-4 according to some aspects of the present disclosure. The computing system 412 may include instructions in the form of computer software for automatically generating images of prosthesis implants in final installation positions on the bone structure images and for automatically generating various guide post images and jig images designed for use during surgery on the particular patient. In some aspects, it may be necessary for the surgeon during preoperative planning to input information into the input device 418 for creating or altering guide post and jig images for a particular patient based on the surgeon's understanding of the particular bone structure of the patient as displayed on the display device 416.

FIGS. 5 and 6 are flow diagrams of methods pertaining to operative surgery according to aspects of the present disclosure. The methods of FIGS. 5 and 6 may be carried out by a surgeon or by a machine, or by both. Moreover, the surgeon may utilize some or all of the devices discussed with reference to FIGS. 1-4A during surgery, such as viewing the preoperative images displayed on the display device while operating on a patient.

In FIG. 5, a method 500 according to an aspect starts at 501. At 502, a first patient-specific jig is positioned in an acetabulum of a patient. The first patient-specific jig is formed according to a predetermined installation position of a prosthesis implant to be secured to the patient. At 504, each of three alignment members is engaged with a corresponding pre-selected area on a coxal bone and adjacent the acetabulum of the patient. At 506, a guide post is positioned through the aperture of the first patient-specific jig and is secured into the coxal bone of the patient. At 508, the first patient-specific jig is removed from the guide post. At 510, bone material from the acetabulum is reamed with aid of a reaming machine. At 512, it is determined whether the reaming machine has reached an installation reference point of the installation position; this may be determined by the surgeon or by a measuring device or other device to determine the depth of bone that was reamed. If the reaming machine has reached an installation reference point, at 514 the guide post is removed and the prosthesis implant is installed in the patient, then ends. If the reaming machine has not reached an installation reference point, at 516 the guide post is removed and a second patient-specific jig is positioned in the reamed acetabulum of the patient, then to step 602 in FIG. 6. As further discussed below, in some aspects the guide post is not removed and remains secured to the patient until the prosthesis implant is installed.

At step 602, three alignment members of the second patient-specific jig are respectively engaged with predefined selected areas proximate the acetabulum of the patient. At 604, a supplemental guide post is positioned through the aperture of the second patient-specific jig and is secured into the coxal bone of the patient. At 606, the second patient-specific jig is removed from the supplemental guide post and the acetabulum. At 608, the acetabulum is reamed with aid of a reaming machine. In some instances the guide post can be removed prior to reaming and the sinus tract in the bone from the guide post is used as a visual guide to ream at a desired orientation and to a desired depth. At 610, a third patient-specific jig is positioned in the reamed acetabulum of the patient. At 612, it is determined whether all three alignment members of the third patient-specific jig are engaged to respective selected areas proximate the acetabulum of the patient. If yes, at 616 the supplemental guide post may or may not be removed and the prosthesis implant is secured to the reamed acetabulum and then ends. If no, the method returns to 608 and the operations are repeated until it is determined that all three alignment members of the third patient-specific jig are engaged to respective selected areas proximate the acetabulum of the patient so that the prosthesis implant may be installed in the patient.

FIGS. 7 and 8 show an acetabular component 700 oriented an in an acetabulum 702 of a coxal bone 704 of a pelvic bone 706. The acetabular component 700 is positioned according to an installation position 708, which is in part determined by a prescribed anteversion angle and a prescribed inclination angle of the acetabular component 700. FIG. 7 shows a front view of the pelvic bone 706 and the acetabular component 700 positioned in the acetabulum 702 of the patient's right coxal bone 704, and FIG. 8 shows a lateral view of the right coxal bone 704 with the acetabular component 700 positioned in the acetabulum 702. These figures illustrate the incorporation of steps discussed with reference to FIGS. 1-4A where the acetabular component 700 is a generated image that is superimposed over a generated image of bone structure (e.g., the coxal bone 704) of a patient to determine an installation position 708 of the acetabular component 700. Determining the prescribed anteversion angle and the prescribed inclination angle for a particular patient involves techniques and calculations that are known in the art, and thus, will not be described in detail. Although not necessarily part of the preoperative planning, for purposes of illustration an installation axis P is shown on FIG. 7

Once the installation position 708 is determined, a reference point 710 is established that represents a particular point in the coxal bone 704 of the patient for purposes of determining the depth to which a reaming machine will ream bone material, which will be further discussed below. The reference point 710 may be considered a point on the tangential plane of a hemispherical shaped surface, such as the outer surface shape of the acetabular component 700.

With continued reference to FIG. 8, the coxal bone 704 includes (among many others) a medial rim 712, a sciatic notch 714, and an obturator foramen 716, which all have various shapes and surfaces that are specific to each patient.

FIGS. 9A and 9B show a patient-specific jig 720 oriented in the acetabulum 702 of the coxal bone 704 according to the installation position 708 of the acetabular component 702. These figures show a technique that incorporates steps of FIGS. 1-4A in that the patient-specific jig 720 is a generated image that is superimposed over the generated image of the bone structure of a patient. As a preliminary matter, the patient-specific jig 720 may be any one of the first, second, and third patient-specific jigs discussed with reference to FIGS. 10A-15B and elsewhere in this disclosure. FIGS. 9A and 9B are mere illustrations of one possible patient-specific jig 720.

The patient-specific jig 720 includes an aperture 722 and three alignment members 724 a, 724 b, 724 c. The aperture 722 is formed through the patient-specific jig 720 at an angle that corresponds to the installation position 708 of the acetabular component 700. Depending upon the particular patient-specific jig 720 (i.e., the first, second, or third), the relative orientation of the aperture 722 may vary depending upon the required amount of bone to be removed and the particular required angle of a reaming head during operation, which is ultimately determined by the installation position 708 of the acetabular component 700. The angles of the various apertures for the various jigs are discussed further below.

The three alignment members 724 a, 724 b, 724 c are attached to the patient-specific jig 720 at positions around a circumference end 726 (or distal end) of the patient-specific jig 720 depending upon the particular bone structure of the particular patient. The three alignment members 724 a, 724 b, 724 c may be formed integral with the jig or may be attached to the jig with any suitable attachment means. The purpose of the three alignment members 724 a, 724 b, 724 c help the surgeon: 1) determine the proper orientation of a guide post to be installed in the patient (FIGS. 13A and 15A), and/or 2) determine whether additional reaming of bone is necessary before utilizing another jig or before final installation of an acetabular component. In any event, depending on whether all of the three alignment members 724 a, 724 b, 724 c of a particular patient-specific jig 720 are in contact with respective selected areas of the patient's bone during surgery when the particular jig is placed in the acetabulum 702, corresponding information is conveyed to the surgeon. The surgeon will be able to determine the next appropriate steps during surgery, as further described below.

The positions of the three alignment members 724 a, 724 b, 724 c will depend on which particular jig (i.e., first, second, or third jigs) the three alignment members are attached to. However, the positions the three alignment members 724 a, 724 b, 724 c may be the same on each jig depending on the preoperative requirements determined by the surgeon and the computing systems. In one example and as shown on FIG. 9B, the first alignment member 724 a is attached to the patient-specific jig 720 at an attachment portion 726 a, and the second alignment member 724 b is attached to the patient-specific jig 720 at an attachment portion 726 b, and the third alignment member 724 c is attached to the patient-specific jig 720 at an attachment portion 726 c. The position of the respective attachment portions 726 a, 726 b, 726 c are determined during pre-operative imaging and planning steps. Accordingly, the three alignment members 724 a, 724 b, 724 c extend from the circumference end 726 of the patient-specific jig 720 and are designed to contact certain selected areas of the coxal bone 704 depending on the bone structure of the patient. The first alignment member 724 a contacts a selected area 728 a of the medial rim 712. The second alignment member 724 b contacts a selected area 728 b of the sciatic notch 714. Finally, the third alignment member 724 c contacts a selected area 728 c inferiorally below the transverse acetabular ligament at the superior portion of the obturator foramen 716. In some instances, such as when using the second and third jigs, the contact between the alignment members and the respective selected areas is dependent upon whether the surgeon has reamed enough bone. If not, at least one of the alignment members will not be in contact with the respective selected area, indicating that more bone needs to be removed, as further discussed below.

FIGS. 10A and 10B show a first patient-specific jig 730. FIGS. 11A and 11B show a second patient-specific jig 744. FIGS. 12A and 12B show a third patient-specific jig 754. These figures represent that the patient-specific jigs are generated images based on the installation position of the acetabulum component and based on the bone structure of the patient. Some or all of the patient-specific jigs are formed by a machine based on the generated images, as further discussed elsewhere in this disclosure. In some cases, only a first patient-specific is generated and created in instances where very little bone reaming is required, for example.

FIG. 10A shows an isometric view of a first patient-specific jig 730 and FIG. 10B shows a side elevational view of FIG. 10A. The first patient-specific jig 730 includes three alignment members 732 a, 732 b, 732 c that extend from a circumference end 734 of the first patient-specific jig 730 at positions to contact certain selected areas of the coxal bone (see FIG. 9A (generically) and FIG. 13B (specifically)). The first alignment member 732 a is attached to the patient-specific jig 730 at an attachment portion 736 a, and the second alignment member 732 b is attached to the first patient-specific jig 730 at an attachment portion 736 b, and the third alignment member 732 c is attached to the patient-specific jig 730 at an attachment portion 736 c. The angle and position of each alignment member 732 a, 732 b, 732 c relative to the circumference end 734 is determined according to the particular position and surface of the selected areas of the coxal bone of the patient that the alignment members 732 a, 732 b, 732 c are designed to contact during use of the first patient-specific jig 730 during operation. Each alignment member 732 a, 732 b, 732 c includes an engagement portion 738 a, 738 b, 738 c, respectively, which is the portion of the alignment member that contacts respective selected areas of the coxal bone 704. See FIGS. 13A and 13B for illustrations of the position of each alignment members 732 a, 732 b, 732 c relative to the first patient-specific jig 730 and the selected areas of the patient's coxal bone 704.

The first patient-specific jig 730 includes an aperture 740 that extends from a reference end 742 to the circumference end 734 of the first patient-specific jig 730. The aperture 740 is sized and configured to receive a guide post positioned in a patient (FIG. 13A). As further described below, the guide post is positioned according to the installation position 708 of the acetabular component 700 (FIGS. 7 and 8). The first patient-specific jig 730 includes a height H1, which is selected so that the reference end 742 does not contact an unreamed acetabulum at the beginning stages of surgery. This is discussed further below.

FIG. 11A shows an isometric view of a second patient-specific jig 744 and FIG. 11B shows a side elevational view of FIG. 11A. The second patient-specific jig 744 includes three alignment members 746 a, 746 b, 746 c that extend from a circumference end 748 of the second patient-specific jig 744 at positions to contact certain selected areas of the coxal bone (see FIG. 9A (generically) and FIG. 15B (specifically)). The alignment members 746 a, 746 b, 746 c are attached to the second patient-specific jig 744 at respective attachment portions 750 a, 750 b, 750 c, similar to the first patient-specific jig 730. The angle and position of each alignment member 746 a, 746 b, 746 c relative to the circumference end 748 is determined according to the particular position and surface of the selected areas of the coxal bone of the patient that the alignment members 746 a, 746 b, 746 c are designed to contact during use of the second patient-specific jig 744 during operation. Such angle and position of each alignment member 746 a, 746 b, 746 c may be the same as or different than that of the alignment members of the first patient-specific jig 730 of FIG. 10A. Each alignment member 746 a, 746 b, 746 c includes an engagement portion 748 a, 748 b, 748 c, respectively, which is the portion of the alignment member that contacts respective selected areas of the coxal bone 704. See FIGS. 15A and 15B for illustrations of the position of each alignment member 746 a, 746 b, 746 c relative to the second patient-specific jig 744 and the selected areas of the patient's coxal bone 704.

The second patient-specific jig 744 includes an aperture 750 that extends from a reference end 752 to the circumference end 748 of the second patient-specific jig 744. The aperture 750 is sized and configured to receive a supplemental guide post positioned in a patient (FIG. 15A). As further described below, the supplemental guide post is positioned according to the installation position 708 of the acetabular component 700 (FIGS. 7 and 8). The second patient-specific jig 744 includes a height H2, which is selected so that, if the reference end 752 contacts a reamed acebaulum, and if at least one of the alignment members 746 a, 746 b, 746 c is not in contact with a respective selected area of the coxal bone, the surgeon will know that additional reaming is necessary before installing the supplemental guide post and placing the final acetabular prosthesis. This is discussed further below. Understandably, height H2 can be greater than height H1, in part because bone is reamed between usage of the first and second jigs.

FIG. 12A shows an isometric view of a third patient-specific jig 754 and FIG. 12B shows a side elevational view of FIG. 12A. The third patient-specific jig 754 includes three alignment members 756 a, 756 b, 756 c that extend from a circumference end 758 of the third patient-specific jig 754 at positions to contact certain selected areas of the coxal bone (see FIG. 9A (generically) and FIG. 17B (specifically)). The alignment members 756 a, 756 b, 756 c are attached to the third patient-specific jig 754 at respective attachment portions 760 a, 760 b, 760 c, similar to the first patient-specific jig 730. The angle and position of each alignment member 756 a, 756 b, 756 c relative to the circumference end 758 is determined according to the particular position and surface of the selected areas of the coxal bone of the patient that the alignment members 756 a, 756 b, 756 c are designed contact during use of the third patient-specific jig 754 during operation. Such angle and position of each alignment member 756 a, 756 b, 756 c may be the same or different to that of the alignment members of the first and second patient-specific jigs of FIGS. 10A and 11A. Each alignment member 756 a, 756 b, 756 c includes an engagement portion 762 a, 762 b, 762 c, respectively, which is the portion of the alignment member that contacts respective selected areas of the coxal bone 704. See FIGS. 17A and 17B for illustrations of the position of each alignment members 756 a, 756 b, 756 c relative to the third patient-specific jig 754 and the selected areas of the patient's coxal bone 704.

The third patient-specific jig 754 includes an aperture 764 that extends from a reference end 766 to the circumference end 758 of the third patient-specific jig 754. The aperture 764 is sized and configured to receive the supplemental guide post positioned in a patient (FIG. 17A). As further described below, the supplemental guide post is positioned according to the installation position 708 of the acetabular component 700 (FIGS. 7 and 8). The third patient-specific jig 754 includes a height H3, which is selected so that, if the reference end 766 contacts a reamed acetabulum, thereby causing at least one of the alignment members 756 a, 756 b, 756 c to not be in contact with a respective selected area of the coxal bone, the surgeon will know that additional reaming is necessary before installing the acetabular component 700 in the patient. This is discussed further below. Understandably, height H3 can be greater than height H2 because bone is reamed between usage of the second and third jigs, and because the second patient-specific jig is used for purposes of positioning the supplemental guide post while the third patient-specific jig is used for purposes of determining whether additional reaming is necessary before installing the acetabular component 700 in the patient.

It will be appreciated that each or all of the alignment members of any one of the patient-specific jigs may be formed in various configuration and shapes. For example, an alignment member may be an arc shaped or other non-linear shaped member, or it may have two or more angles surfaces. The exact shape, position, and alignment of each alignment member is determined by the surgeon and the computing system during preoperative planning depending upon the specific bone structure of the patient and the installation position of the acetabulum component.

FIGS. 13A and 13B show the first patient-specific jig 730 positioned in an un-reamed acetabulum 703 of the patient, and FIG. 14 shows a reaming tool 768 positioned in the acetabulum 703 and ready to ream bone material. These figures show a technique that incorporates the preoperative steps of FIGS. 1-4A in that the first patient-specific jig 730 and a guide post 770 are generated images that are superimposed over the generated image of the bone structure of a patient. These figures also show a technique that incorporates the operative steps practiced by a surgeon on a patient, such as described with reference to FIGS. 5 and 6.

During preoperative planning and with reference to FIGS. 9A and 9B, a generated image of an acetabular component 700 is imposed over the bone structure image, which ultimately shows the installation position 708 of the acetabular component 700. Based on such installation position 708, the computer system determines, with input from the surgeon, the exact position of the guide post 770 to be installed in the patient during early stages of operation. The guide post 770 will be the guide for the position of the first patient-specific jig 730 and the reaming machine 768. Preferably, the guide post 770 is positioned substantially perpendicular to a central axis of the acetabular component 700 to be later installed in the patient; however, the angle of the guide post 770 relative to the acetabular component 700 may vary depending upon the preoperative surgery analysis by the computer system and the surgeon based on patient requirements. Once the orientation of the guide post 770 is established and displayed as a generated image, an image is generated of the first patient-specific jig 730. As noted above, the purpose of the first patient-specific jig 730 is to establish the exact position of the guide post 770 to be installed in the patient during surgery. Accordingly, the reference end 742 of the first patient-specific jig 730 is designed to make contact with the un-reamed acetabulum 703. The three alignment members 732 a, 732 b, 732 c are designed to contact respective selected areas of the coxal bone 704 adjacent the acetabulum 703.

With particular reference to FIG. 13B, during surgery the surgeon inserts the first patient-specific jig 730 into the acetabulum 703 and rotates or otherwise orients the first patient-specific jig 730 in the patient until all three alignment members 732 a, 732 b, 732 c are in contact with respective selected areas 772 a, 772 b, 772 c of the coxal bone 704. Once the first patient-specific jig 730 is properly oriented, the surgeon inserts the guide post 770 through the aperture 740 and screws the guide post 770 into the bone (typically 2 mm to 20 mm deep). Thus, the guide post 770 will be installed at the exact position determined during preoperative planning and according to the installation position of the acetabular component 700. The first patient-specific jig 730 may then be removed and a reaming machine 768 may be used to remove bone material from the patient, either over the guide post or without it in place.

FIG. 14 illustrates the reaming machine 768 used for such purpose. The reaming machine 768 includes a reaming head 774, which may be a detachable head of a selected size corresponding to the size of the acetabular component 700 to be installed. The reaming head 774 includes a guide aperture 776 that slidably receives the guide post 770. The reaming head 774 reams bone with a consistent axial motion in a direction depicted by Arrow A because the guide aperture 776 includes a central axis coextensive with a central axis of the guide post 770 and because the guide aperture 776 closely receives the guide post 770. Such reaming heads with a guide aperture and methods of using such reaming heads with a guide post in a patient are well known in the art and will not be described in greater detail.

FIGS. 15A and 15B show the second patient-specific jig 744 positioned in a reamed acetabulum 705 of the patient, and FIG. 16 shows a reaming tool 768 ready to ream additional bone material. These figures show a technique that incorporates the preoperative steps in that the second patient-specific jig 744 is a generated image that is superimposed over the generated image of the bone structure of a patient. These figures also show a technique that incorporates the operative steps practiced by a surgeon on a patient.

FIG. 15A shows the reamed acetabulum 705 as the result of the surgeon reaming a portion of the acetabulum 703 to a desired depth. In some instances, the surgeon will ream a couple millimeters of bone and will have reached the reference point 710 (FIG. 7) such that bone reaming is completed and the acetabular component 700 can be installed in the patient. In other instances, additional bone reaming is necessary to a depth depending upon the installation position 708 for a particular patient as determined during preoperative planning. When it is determined that additional bone reaming is necessary, in some instances the guide post 770 of FIG. 13A remains installed in the patient and the second patient-specific jig 744 is utilized to determine if additional bone reaming is necessary; this is accomplished by inserting the second patient-specific jig 744 into the reamed acetabulum 705 over the guide post 770 and determining whether the three alignment member 746 a, 746 b, 746 c are all in contact with selected areas 772 a, 772 b, 772 c of the coxal bone 704. If not, the surgeon may utilize the reaming machine 768 of FIG. 14 and ream additional bone material. The surgeon may continue to check the depth of the reamed acetabulum 705 by utilizing the second patient-specific jig 744 as noted above until all three alignment members 746 a, 746 b, 746 c are in contact with the selected areas 772 a, 772 b, 772 c of the coxal bone 704. Once this is achieved, the surgeon will know with accurate precision that the reference point 710 has been reached and at the desired angle for accurate installation of the acetabular component 700 in the patient. The surgeon may then install the acetabular component 700 in the patient utilizing known techniques in the art. In the current method, a guide post may be utilized over which the acetabular component 700 may be more accurately placed than with standard techniques.

In other instances and where additional bone reaming is necessary but at a different angle than with respect to FIG. 14 according to preoperative planning, the guide post 770 is removed from the patient and a supplemental guide post 778 is installed in the patient to guide the reaming machine 768 at a different angle than the original guide post 770. In some instances the supplemental guide pst 778 may be removed prior to reaming and the sinus tract in bone may guide the surgeon to ream at an appropriate angle and to an appropriate depth. Such operative steps are determined by the surgeon, with the use of the computing system, during preoperative planning. For purposes of illustration and as one example, FIGS. 15A and 15B show the supplemental guide post 778 installed in the patient at a different angle than the guide post 770 of FIGS. 13A and 14. Accordingly, once the bone is reamed as described with reference to FIG. 14, the guide post 770 is removed and the second patient-specific jig 744 is placed into the reamed acetabulum 705. Similar to the first patient-specific jig 730, the second patient-specific jig 744 is utilized to determine the orientation of the supplemental guide post 778 to be installed in the patient. Thus, the surgeon inserts the second patient-specific jig 744 into the reamed acetabulum 705 and rotates or otherwise orients the second patient-specific jig 744 in the patient until all three alignment members 746 a, 746 b, 746 c are in contact with respective selected areas 772 a, 772 b, 772 c of the coxal bone 704, as depicted on FIGS. 15A and 15B. Once the second patient-specific jig 744 is properly oriented, the surgeon inserts the supplemental guide post 778 through the aperture 750 and the threads of the supplemental guide post 778 engage the bone. Thus, the supplemental guide post 778 will be installed at the exact position determined during preoperative planning and according to the installation position of the acetabular component 700. The second patient-specific jig 778 may then be removed and a reaming machine 768 may be used to remove additional bone material from the patient, with or without the guide post in place.

FIG. 16 illustrates the reaming machine 768 used for such purpose. The reaming machine 768 includes a supplemental reaming head 780, which may be a detachable head of a selected size corresponding to the size of the acetabular component 700 to be installed. The supplemental reaming head 780 may be smaller in size than the reaming head 774 of FIG. 14, or it may be the same size. The supplemental reaming head 780 may include a guide aperture 782 that slidably receives the supplemental guide post 778. The supplemental reaming head 780 reams bone with a consistent axial motion in a direction depicted by Arrow B because the guide aperture 782 includes a central axis coextensive with a central axis of the supplemental guide post 778 and because the guide aperture 782 closely receives the supplemental guide post 778. Such reaming heads having a guide aperture are well known in the art and will not be described in greater detail.

FIGS. 17A and 17B show the third patient-specific jig 754 positioned in a reamed acetabulum 707 of the patient. These figures show a technique that incorporates the preoperative steps of FIGS. 1-4A in that the third patient-specific jig 754 is a generated image that is superimposed over the generated image of the bone structure of a patient. These figures also show a technique that incorporates the operative steps practiced by a surgeon on a patient disclosed herein.

FIG. 17A shows a reamed acetabulum 707 as the result of the surgeon reaming a portion of the acetabulum 705 to a desired depth, as discussed with reference to FIG. 16. In some instances, the surgeon will ream one or two millimeters of bone and utilize the third patient-specific jig 754 to determine whether additional bone reaming is necessary before final installation of the acetabular component in the patient, as determined during preoperative planning. Thus, the surgeon inserts the third patient-specific jig 754 into the reamed acetabulum 707. If all three alignment members 756 a, 756 b, 756 c are in contact with respective selected areas 784 a, 784 b, 784 c of the coxal bone 704, then the third patient-specific jig 754 has indicated that the reference point 710 of the installation position 708 has been reached, and therefore, bone reaming is completed.

The surgeon will then install the acetabular component 700 according to known techniques or over a supplemental guide post using a cannulated acetabular impactor and mallet device as described herein. For purposes of discussion, FIG. 17A shows that alignment member 756 b is not in contact with the selected area 784 b adjacent to the native acetabulum. As such, the illustrated third patient-specific jig 754 indicates that the reference point 710 has not been reached, and, therefore, additional bone reaming is necessary. Accordingly, the surgeon reams bone with the reaming head 780, utilizing the supplemental guide post 778 pilot hole or sinus tract from the removed guide post as a guide member, and then inserts the third patient-specific jig 754 to determine whether all three alignment members 756 a, 756 b, 756 c are in contact with the coxal bone 704 and the reference point 710 (FIG. 7) has been reached by the supplemental reaming head 780. These processes continue until the acetabulum is reamed to the desired depth of the reference point, at which point the surgeon installs the acetabular component 700 in the patient, as shown on FIG. 8.

FIGS. 18-22 show aspects of the present disclosure in which an impactor tool 800 is used to assist with installation of an acetabular component 700 in a reamed acetabulum 705 or 707. Typically, a reamed acetabulum is reamed to have a radius slightly smaller than the radius of the acetabular component for a tight fit configuration. As such, the surgeon typically utilizes a mallet or other tool to impact the acetabular component into its final position.

The impactor tool 800 includes a head 802 and a handle 804. The head 802 includes a guide aperture 806 having a central axis X. During surgery and once the acetabulum is reamed to a desired depth, the acetabular component 700 is partially inserted into the reamed acetabulum. An elongated guide post 808 is installed in the coxal bone 704 and extends through a hole in the acetabular component 700, as known in the art. A cannulated acetabular impactor device 810 includes a cannulated channel 812 that receives the elongated guide post 808; the cannulated acetabular impactor device 810 may be threaded or slidably received over the elongated guide post 808. The cannulated acetabular impactor device 810 includes a distal end 814 biased against the cup portion of the acetabular component 700, and a proximal end 816 with a surface 818 to be impacted by the impactor tool 800. The guide aperture 806 of the impactor tool 800 slidably receives a portion of the guide post 808.

During installation of the actabular component 700, the surgeon holds the handle 804 and slidably engages the guide aperture 806 of the impactor tool 800 with the guide post 808. The surgeon then repeatedly impacts the surface 818 of the proximal end 816 of the cannulated acetabular impactor device 810 with the impactor tool 800, causing an impacting force against the acetabular component 700, until the acetabular component 700 is in its final position. Typically several impacts with the impactor tool 800 will suffice, and typically the surgeon can hear when the acetabular component 700 is seated flush against the acetabulum in its final position. One advantage of the impactor tool 800 is that impact against the elongated member 810 (and ultimately the acetabular component 700) occurs at approximately the same impact location upon each repeated impact with the tool 800. Typically, the surgeon uses a mallet or hammer without the assistance of any guidance, which can result in improper installation of the acetabular component 700. The guide aperture 806 of the impactor tool 800 ensures repeatable impact location and position of the impactor tool 800, which reduces or eliminates the possibility for human error during repeated impacts with a mallet or hammer.

The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure. 

1-22. (canceled)
 23. A method, comprising: using at least one bone surface image to generate three dimensional data corresponding to a bone structure of a patient; generating a prosthesis implant image superimposed over an image of an acetabulum and positioned according to a final installation position based on the three dimensional data; generating a patient specific jig image superimposed over the image of the acetabulum according to the installation position, the patient specific jig image having a body with at least three alignment members at positions corresponding to the installation position of the prosthesis implant image; and generating control data from the patient specific jig image, the control data configured to control operation of a machine for making a patient-specific jig.
 24. The method of claim 23 wherein generating a prosthesis implant image includes generating a guide post image at least partially positioned through the image of the acetabulum, the guide post image oriented corresponding to the installation position of the prosthesis implant image.
 25. The method of claim 24 wherein generating the patient-specific jig image includes generating an aperture image through the body image of the patient-specific jig image, said aperture image in a position corresponding to the guide post image.
 26. The method of claim 24, further comprising generating a second patient-specific jig image superimposed proximate the image of the acetabulum, the second-patient specific jig image having a body image with at least three alignment member images corresponding to the installation position of the prosthesis implant image.
 27. The method of claim 26 wherein generating the second patient-specific jig image includes generating an aperture image through the body image of the second patient-specific jig image, said aperture image in a position corresponding to the guide post image.
 28. The method of claim 26, further comprising generating a third patient-specific jig image superimposed proximate the image of the acetabulum, the third patient-specific jig image having a body image with at least three alignment member images corresponding to the installation position of the prosthesis implant image.
 29. The method of claim 28 wherein generating the third patient-specific jig image includes generating an aperture image through the body image of the second patient-specific jig image, said aperture image in a position corresponding to the guide post image.
 30. The method of claim 29, wherein the body images of the patient specific jig, the second patient specific jig, and the third patient specific jig have different distances between respective proximal and distal ends thereof.
 31. A method, comprising: positioning a first patient-specific jig in an acetabulum of a patient, the first patient-specific jig formed according to a predetermined installation position of a prosthesis implant to be secured to the patient, the first patient-specific jig having an aperture and three alignment members attached at respective positions to the first patient-specific jig corresponding to the installation position of the prosthesis implant; engaging each of said three alignment members to a predefined selected area of a coxal bone adjacent the acetabulum of the patient; positioning a guide post through the aperture of the first patient-specific jig and securing the guide post to the patient, the guide post positioned corresponding to the installation position of the prosthesis implant; removing the first patient-specific jig from the guide post; and reaming the acetabulum with a reaming machine, the guide post configured to guide the reaming machine in a desired position during reaming, with or without the guide post in place.
 32. The method of claim 31, further comprising: determining whether the reaming machine reached a reference point of the installation position; if the reaming machine reached the reference point, removing the guide post and installing the prosthesis implant in the patient using a second patient specific jig and over a guide post; if the reaming machine has not reached the reference point, removing the guide post and positioning a second patient-specific jig in the reamed acetabulum of the patient, the second patient-specific jig formed according to the predetermined installation position, the second patient-specific jig having an aperture and three alignment members disposed at respective positions on the second patient-specific jig corresponding to the installation position; engaging each of said three alignment members to a predefined selected area of the coxal bone proximate the acetabulum of the patient; positioning a supplemental guide post through the aperture of the second patient-specific jig and securing the supplemental guide post to the patient, the supplemental guide post positioned corresponding to the installation position of the prosthesis implant; removing the second patient-specific jig from the supplemental guide post and the acetabulum; and reaming the acetabulum with a reaming machine, one of the supplemental guide post and the pilot hold sinus tract being used to guide the reaming machine in a desired position during reaming.
 33. The method of claim 32, further comprising: positioning a third patient-specific jig in the reamed acetabulum of the patient, the third patient-specific jig formed according to the predetermined installation position, the third patient-specific jig having an aperture to receive the supplemental guide post, the third patient-specific jig having three alignment members disposed at respective positions on the third patient-specific jig corresponding to the installation position of the prosthesis implant; determining whether each of said three alignment members of the third patient-specific jig are engaged to said selected area proximate the acetabulum of the patient; if each of said three alignment members of the third patient-specific jig are not engaged to said selected area, repeating said reaming operation of the previous claim and the positioning operation of the present claim until all of said three alignment members of the third patient-specific jig are engaged to said selected areas, respectively; and if each of said three alignment members of the third patient-specific jig are engaged to said selected area, thereby indicating information that the installation reference point has been reached, securing the prosthesis implant to the reamed acetabulum over the guide post, with or without the guide post in place.
 34. The method of claim 32 wherein securing the prosthesis implant includes impacting the prosthesis implant with an impactor tool, the impactor tool having a guide aperture with a central axis and configured to slidably receive a guide post secured to the patient.
 35. The method of claim 34 wherein impacting the prosthesis implant with the impactor tool comprises repetitively impacting the prosthesis implant such that the guide aperture repetitively guides the impactor tool along the central axis, whereby each impact occurs approximately at the same impact point relative to the prosthesis implant.
 36. The method of claim 35 comprising engaging a cannulated acetabular impactor device with the prosthesis implant, the cannulated acetabular impactor device having an aperture that receives the guide post, the cannulated acetabular impactor device having a first end biased to the prosthesis implant and a second end for impacting with the impactor tool.
 37. A tool used for a joint replacement prosthesis comprising a body usable to cause impact to a prosthesis implant positioned in an acetabulum of a patient, the body having an aperture with a central axis, the aperture configured to slidably receive a guide post secured to a bone of the patient and configured to guide the body along the guide post.
 38. The tool of claim 37 wherein the central axis of the guide aperture is coextensive with a central axis of the guide post.
 39. The tool of claim 37 wherein the aperture is configured to repetitively guide the body along the guide post such that impact caused against the prosthesis implant occurs substantially at the same impact point relative to the installation position.
 40. The tool of claim 37 wherein the body is configured to impact the prosthesis implant via an elongated member positionable between the prosthesis implant and the tool.
 41. A device for use in implanting an acetabular cup having an exterior surface for being positioned against a patient and an opposing interior surface, the device comprising: an elongated shaft having an opening extending the length thereof; an enlarged impacting end having an exterior surface shaped to complement the interior surface of the acetabular cup, the impacting end having an opening extending therethrough, the opening being aligned with the opening in the elongated shaft; and a striking end, opposite the enlarged impacting end, the striking end having an opening therethrough, the opening being aligned with the opening in the elongated shaft.
 42. The device of claim 41, further comprising: a rod sized to be received by the openings in the elongated shaft and impacting and striking ends of the device, the shaft being sufficiently long to project beyond both terminal ends of the device, a first end of the elongated shaft being adapted for engagement with the patient; and a weighted mass having an opening therethrough adapted to closely receive the rod such that the mass can slide along the rod and collide with the striking end of the device at one terminal end of its stroke, the rod maintaining the mass and the device in a desired alignment for seating the acetabular cup.
 43. The method of claim 31 wherein the patient is a human. 